The acf/load_field hook and filters can be used in the admin, I’ve looked at it and I don’t think there is anything about the text field that can be modified to display an image.
There aren’t any fields or filters that will allow you do do this in ACF. This would require building a new custom field type (http://www.advancedcustomfields.com/resources/creating-a-new-field-type/). There may already be an add on somewhere out there that does this but it’s nothing that I’ve seen before.
